Topic: 79 CB650 carburetors

[CBR954AD]

Thanks for feedback.  So the reason why the tube is kinked is so I can get the tube as parallel as I can to carb. When I open the drain at first and wait about 10 sec I have then i try to remove kink for flow. . I know it can restrict flow. Yes they are not exactly 3-4 mm under . At this point I'm just trying to get them to stop leaking and will fine tune once I can fix the leak.
So after thinking for while I realized these carb I bought off eBay. The original carbs are in box all in pieces and missing parts. That's why I bought these. What if this is bad carb on number 1? Like has crack somewhere.?
By replacing needle and float from 4 number one should have not leaked.
Yes they are plastic tipped needles. I have all brand new OEM . All same lenght
DaveBarbier: the picture on how to properly use clear tube method cannot be done like that on my carbs. The drain is straight down so you will always have a kink in the tube.

[DaveBarbier]

Use a more flexible tube then. Don’t allow kinks in the tube.

[CBR954AD]

  3mm would be at the bottom of the Phillips head which holds the bowl. as seen on the image.

[CBR954AD]

its pretty fleble clear tube. if i dont allow kinks it would have a huge radius, thus giving inaccurate measurement. honestly the kink here is not the issue.

[DaveBarbier]

its pretty fleble clear tube. if i dont allow kinks it would have a huge radius, thus giving inaccurate measurement. honestly the kink here is not the issue.

I’m sorry but your understanding of the method is incorrect, it doesn’t matter how much tube you have the principal will work the same. You could have a length of tube go down the street as long as it’s lower than the carb bowl. It’s the water level principal. Use more tube and give a larger radius.

But it is IMPERATIVE, that you first hold the tube in place still and THEN open the drain screw and NOT move the tube until you see the level.

And yes, as the picture shows, 3mm is pretty much right below the screw head. So what? 3-4mm is what you want.

[CBR954AD]

Ok guys, I'm back at it. I installed my spare #1 carb used all component from carb #4 which we know does not leak. The bike is on side stand, I open petcock and 1 starts leaking again, once I start the bike it stops leaking.
I thought I might have a internal crack somewhere this is why I replaced number one. But it did not fix the issue. I know my fuel float level is NOT exactly at 3mm. On #4 it's probably to lean close to 5mm so it should not be leaking but it is still leaking. I installed everything back on #4 meaning float and needles without changing anything and four is solid like before.
Am I missing something?
When I took #1 out I checked all my O rings they are all there.

[DaveBarbier]

So it’s still leaking through the bowl seam. Your float height is still too high, maybe you’re not doing the clear tube method correctly. When the bike is running it’s using fuel, lowering the level so it doesn’t leak.

OR, your floats are hanging up and not closing the needle valve. OR your needle valve seat is damaged and not sealing.

I have a feeling there’s miscommunication and confusion going on on your part though.

Carbs are not that difficult to work with, nothing magical going on. If fuel is leaking out the bowl seam, too much fuel is being delivered into the bowl for some reason.

I also feel you’re jumping around more than you should. Replacing parts and carb bodies. I think you should set float height with the clear tube method first. Get that nailed and work from there.

[CBR954AD]

Does anyone know how to remove the float needle seat? And where to order one from?
On my carb the seat is brass and pressed in the body.

[RAFster122s]

To the best of my knowledge the carb needle seats are not replaceable. Never heard of anyone trying to do so... If your needle seat is damaged you will likely need to replace the carb body.

You should be able to test the needle and seat with the float bowl off and petcock on. When you bring the float up it should turn off the fuel flow. If it does not, then you have a damaged or dirty seat or damaged float needle.
David

[CBR954AD]

I emailed ultrasonic guy on for sale section. He does carb rebuilds. I told him what's going on. He said it's most likely the needle seat. However I replaced the carb with another. I highly doubt 2 carbs are bad. Possible but I doubt it
I do see the part on part diagram it's like $16, but unavailable from bike bandit and other part sellers.
I also did mention to Alex the ultrasonic carb guy the seat looks like it is pressed in and he did not get back to me on that matter.
I did find a way to test the seat and needle though.
Take carb connect shop air 10psi or mighty van on pressure. Insert the needle in seat, place the carb under water. Push on needle lightly and feed air . If we see bubble there is a leak.

[CBR954AD]

To the best of my knowledge the carb needle seats are not replaceable. Never heard of anyone trying to do so... If your needle seat is damaged you will likely need to replace the carb body.

You should be able to test the needle and seat with the float bowl off and petcock on. When you bring the float up it should turn off the fuel flow. If it does nothing, then you have a damaged or dirty seat or damaged float needle.
David

Hi. So I did this test on bench with air not fuel, and I do hear the air being cut off from needle. No I have not test it with fuel flow. I can test it on bench with fuel and get back to you.

[CBR954AD]

Ok guys, carburetor are not leaking anymore. I sat down and adjust each one . I have video of bike running. Now I have few more issues.
1: when I pull out spark plug wire on cylinder 1 ,while engine running, or on cylinder 4 bike dies. I do same on cylinder 2 or 3 bike runs but only on 3 cylinders.
Can I swap coil pack and see if it does same thing? Or look else where?
2: oil spraying from a hole on the head see image.
3: I have aftermarket speedo/ tach. But tach not working. Manual says to wrap the yellow wire coming from tach around sparkplug wire on cylinder 1. Nothing else
https://photos.app.goo.gl/6s89npnimsAvsLmG6
https://photos.app.goo.gl/eFJpHwHAmQ8yr7NfA

[scunny]

That hole is meant to have a bolt in there, it secures the top of the cam chain tensioner.
11 & 9

[CBR954AD]

Thank you
Do you know the lenght of the bolt? I must have forgotten to install it once I put the engine back together

[RAFster122s]

I think you are going to have to open the motor up to secure the tensioner properly. Should have the bolt size identified in the parts manual page showing the tensioner. Look it up for your model and year in the parts exploded diagrams for ordering from a place like southsoundhonda.com

[CBR954AD]

I remember installing all parts from part numbers 5,6,7,9,10 . Why do you think I need to open the motor if the bolt goes out to in it just pressed on the tensioner.

[DaveBarbier]

Bike sounds pretty good. Why are you concerned about how the bike performs when you pull plug wires? Are all exhaust pipes hot to the touch? Lick your finger and tap each header, you should feel about the same amount of pain. Or spray with water if you’re a wimp.

I wouldn’t run the motor anymore until you get that bolt installed. It also has a copper crush washer to seal the oil, don’t forget that.

As for the tachometer, what happens when you wrap that yellow wire around a plug wire? In your video the tach was working, wasn’t it?

[CBR954AD]

So it looks like the the tach is getting signal but very vauge. When I blip throttle it does not move right away. Or sometime s it will jump up. I have digital temp gun, but my battery died on it. Yes all 4 pipes are hot.
I'm just concerned because when I pull one spark plug the bike should not die and it only does it on coil for cylinders 1,4.
I ordered the bolt and washer just now.
I also checked my timing in dynamic mode w timing gun I'm at 12 deg . Manual say 10.

[DaveBarbier]

So it looks like the the tach is getting signal but very vauge. When I blip throttle it does not move right away. Or sometime s it will jump up. I have digital temp gun, but my battery died on it. Yes all 4 pipes are hot.
I'm just concerned because when I pull one spark plug the bike should not die and it only does it on coil for cylinders 1,4.
I ordered the bolt and washer just now.
I also checked my timing in dynamic mode w timing gun I'm at 12 deg . Manual say 10.

Have you ridden it yet? Does it feel fairly smooth without hiccups?

Don’t worry about the idle timing, what matters is the full advance timing. Get that as close as you can and as long as the idle timing isn’t WAY off then you’re totally fine.

If all headers are equally hot and the bike runs and idles good I honestly wouldn’t worry about what happens when you pull a plug wire. You could check that your plug gap is within spec and you could do a compression check but if that all checks out (unless any other members have reservations) I’d just enjoy your bike! Have you synced your carbs? That may help.

As for that tach, I can’t help you. Maybe you need to try a different plug wire or wrap the wire more times? Or maybe route the wire so it doesn’t get electromagnetic interference from other wires? That yellow signal wire is kind of like an antenna and sensitive to EMI. Can you contact the company for tech support? It’s possible you have a faulty unit. Maybe try on a different bike if you have access to one?

[CBR954AD]

I have never ride the bike yet. I just finally after 1 year fixed the carburetors. This is my 1st bike build . I completely rebuild the engine. However it's not my first engine build. I'm almost ready for first shakedown. Still need to sort out few things like clutch. I need to adjust. As soon as I put in gear and drop bike dies, like it's to tight. I'm pretty sure it's adjustments issue, . Plus I have to take bike to state part inspection to register it. I bought the bike 4 years ago in pieces with loss title. I did complete custom rebuild,  will post pix. Running 80 gl1000 front end dual disc, 79 750 swing arm . 750 wheels, custom seat, and wire tuck.